Adopt C99 <stdint.h> integer types.

The annoying int64.h is completely retired, since C99 guarantees a
64-bit integer type that you can actually treat like an ordinary
integer. Also, I've replaced the local typedefs uint32 and word32
(scattered through different parts of the crypto code) with the
standard uint32_t.

sftpserver.c

@@ -16,7 +16,7 @@ struct sftp_packet *sftp_handle_request(
     struct sftp_packet *reply;
     unsigned id;
     ptrlen path, dstpath, handle, data;
-    uint64 offset;
+    uint64_t offset;
     unsigned length;
     struct fxp_attrs attrs;
     DefaultSftpReplyBuilder dsrb;